dunderheaded

/ˈdʌndərˌhɛdɪd/
adjective
  1. Stupid, slow to understand, or lacking common sense.
    • He made a dunderheaded mistake by leaving his keys in the locked car.
    • My dunderheaded friend tried to open the door by pushing when it clearly said 'pull.'
    • The dunderheaded plan to build a sandcastle at high tide was doomed from the start.
What does "dunderheaded" mean? | whatsthatwordmean | whatsthatwordmean